Raised levels of interleukin 6 in systemic lupus erythematosus correlate with anaemia.

ABSTRACT

OBJECTIVES: Raised levels of the cytokines interleukin (IL) 6 and IL10 have been reported in patients with systemic lupus erythematosus (SLE). OBJECTIVE: To determine if levels of IL6 and IL10 correlate with organ/system-specific disease activity in SLE, using the British Isles Lupus Assessment Group (BILAG) Disease Activity Index. METHODS: Levels of IL6 and IL10 in serum samples from 171 patients with SLE and 50 normal controls were determined by enzyme linked immunosorbent assay (ELISA). Levels of cytokines in individual patients with SLE were compared with the presence or absence of active disease in eight organ/systems using the BILAG index. RESULTS: Levels of IL6 were significantly higher (p = 0.005) in patients with active compared with inactive haematological disease, as scored by the BILAG index. Further analysis showed that this association was dependent on an inverse correlation (p = 0.002, r = -0.26) between IL6 levels and haemoglobin levels in patients with SLE. In contrast, IL10 levels did not correlate with individual organ/system disease activity. CONCLUSIONS: Raised levels of IL6 in SLE may influence the development of anaemia in this disease. These findings are in agreement with an increasing number of studies, which support physiological links between IL6 and anaemia. Importantly, with the exception of the haematological system, our studies do not provide evidence of any individual organ/system which would respond to therapeutic manipulation of either IL6 or IL10 levels.